Berghoff, Luisa (2012) Effects of changing temperature and nutrient supply on heterotrophic and autotrophic nanoflagellates. (Bachelor thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 45 pp.

Text Bachelor_thesis - LuisaBerghoff.pdf - Published Version Restricted to Registered users only Available under License German copyright act UrhG. Download (2MB) | Contact

Abstract

The response of heterotrophic and autotrophic nanoflagellates to changing temperature and nutrient supply was studied in a mesocosm experiment from May to June of 2012, in which we manipulated temperature conditions and nutrient availability. Corresponding to the temperatures in situ and predicted sea surface warming by 2-6 °C at the end of this century (IPCC, 2007), the experiment was conducted with warming of 3 °C (ΔT = +3 °C) and cooling of 3 °C (ΔT = -3 °C). Six nutrient treatments were defined according to the predicted effect of warming on nutrient supply in the North Atlantic (HOFFMAN et al. 2009). The light scenario mimicked the natural irradiance according to the astronomic model of BROCK (1981), cloud cover and underwater attenuation. Higher abundances of heterotrophic nanoflagellates (HNF) were found under increased temperatures, while cooled conditions presented overall low HNF cell numbers. The defined nutrient treatments showed no significant influence on autotrophic nanoflagellates (ANFs) in the course of the experiment, whereas analyses of other phytoplankton presented positive responses to increased nutrient treatments. In the future, it will be necessary to analyse potentially direct and indirect influences of changing conditions on predator-prey dynamics and the competition of resources among same trophic cascades of the microbial loop and the pelagic food web system. The investigation of interrelated influences and potentially changing key roles within the marine pelagic ecosystem help to understand the effects of climate warming and changing nutrient supply. Warming, in particular, could edge ahead the importance of microbial processes and therefore the role of the nanoflagellate community and its meaning for present-day marine ecosystems.

Actions (login required)

View Item